FACTORS AFFECTING THE DEGRADATION OF BISPHENOL A BY ACTIVATED SLUDGE

ANA MICAELA FERRO OROZCO; EDGARDO MARTIN CONTRERAS; NOEMI ELIZABET ZARITZKY

LAP LAMBERT Academic Publishing

Año: 2016 p. 65

978-3-659-86581-7

Bisphenol A (BPA) has beendescribed as a estrogenic compound. However, it is used in the production of polycarbonate,epoxy resins and other plastics. Mixed microbial cultures, such as activatedsludge, have been proposed as a feasible methodology to achieve thedecontamination of wastewater containing BPA.In this book, the biodegradationof bisphenol A (BPA) using activated sludge not previously exposed to BPA(native activated sludge) was described. In addition, theacclimation process to BPA and the strategies of acclimation of the biomass tothe xenobiotic compound were analyzed. The kinetics and stoichiometry of thebiodegradation of BPA and its metabolic products were determined. Finally, thebiodegradation of BPA in the presence of a biogenic substrate insemi-continuous activated sludge reactors was studied.  Results demonstrate that BPA concentrations lower than40 mg L-1 had a negligible effect on the growth of native activatedsludge.Activated sludge (AS) samples from reactors operatedat sludge ages (SA) of 30 and 45 days were acclimated to BPA using twostrategies: constant or increasing the initial BPA concentration. Althoughacclimation to BPA was achieved using both strategies, no net biomass growthwas detected. Specific BPA degradation rate of acclimated AS ranged from 65 to90 mgBPA gTSS-1 d-1. BPA degradation was not affected bythe biogenic substrates (cheese whey or acetate); acclimation to BPA did notcause a negative effect on the biodegradation of these substrates. During thedegradation of cheese whey, specific mean oxygen uptake rate (qO2mean)and specific mean substrate consumption rate (qSmean) ofnon-acclimated AS were similar to those corresponding to acclimated ones. Whenacetate was tested, qO2mean and qSmean valuescorresponding to acclimated AS were about twofold the values of thenon-acclimated ones. This enhancement of the biodegradation process occurredbecause acetate is an intermediate of the metabolism of BPA.The kinetics of thebiodegradation of BPA and its metabolic products, 4-hidroxyacetophenone (4HAP),4-hidroxybenzaldehyde (4HB) and 4-hidroxybenzoic acid (4HBA), was influenced bythe sludge age, the acclimation process, and the concentration of the analyzedcompound. The stoichiometry of the reactions was not affected by the studiedconditions. The average oxidation coefficients YO/S were 10.0 ± 0.5,5.2 ± 0.2, 3.7 ± 0.2, and 3.0 ± 0.1 molO2 molS-1 for BPA,4HAP, 4HB, and 4HBA, respectively. Based on the obtained YO/Svalues, a biodegradation pathway was suggested. Additionally the simultaneousdegradation of BPA and cheese whey (CW) in semi-continuous activated sludgereactors was studied. The acclimation process and the microbial growth on BPA,CW and BPA+CW were analyzed; the effect of increasing CW concentration on theBPA degradation by acclimated activated sludge was also studied. In thesemi-continuous reactors, the presence of CW increased the acclimation time to 40 mg L-1 of BPA. Oncethe capability of degrading BPA was acquired, the removal of BPA was not affectedby the presence of CW. Increasing the CW concentration did not affect theremoval of BPA by the acclimated activated sludge. Additionally, the CWconsumption was not modified by the presence of BPA. Kinetic and stoichiometriccoefficients can be useful in developing mathematical models to describe thesimultaneous aerobic biodegradation of a biogenic substrate, such as CW, andBPA by activated sludge.